Load distributory and articulating system in all terrain vehicle of a traction and terrain

ABSTRACT

A load distributing and articulating system in an all terrain vehicle of a tractor and a trailer arranged along a longitudinal axis. The trailer has a trailer body with a load section thereon. The system comprises a first pivot for articulating rotation between the tractor and the trailer in a vertical plane perpendicular to the longitudinal axis, about the longitudinal axis; a second pivot for articulating rotation between the trailer body and the load section, in a vertical plane along the longitudinal axis, about an axis perpendicular to the longitudinal axis; at least two variable length actuators disposed between the tractor and the load section for controlling rotation about said first and second pivots; an adjustable controller for varying the lengths of the variable length actuators independantly of each other; and a device for preventing the adjustable controller from varying the lengths of the variable length actuators, and for enabling variation of the lengths thereof.

The present invention relates to a transmission and articulationarrangement between a terrain vechicle and a trailer.

Terrain vehicles known today, for example of the type shown by FinnishPatent Application No. 854777, have an articulation of rotation betweena tractive vehicle and a trailer. This articulation provides forrotating movement of the two sections relative to each other in avertical plane perpendicular to the driving direction during theoperation in the terrain. The articulation of rotation is furtherequipped with an actuator, such as a hydraulic cylinder, which isattached at its ends respectively to the opposite sides of thearticulation of rotation and which can be immobilized at a desiredlength thereof in order to make the articulation of rotation immobile.

The devices of the type explained above have often the need ofadjustment of weight to various points longitudinally of the vehiclecombination. For providing such an operation, an actuator is mountedbetween the body of the trailer and a body section pivotable on the bodyin a vertical plane extending longitudinally of the vehicle. Theactuator provides for pivoting of said load section and accomplishes sothe desired weight distribution in the longitudinal direction of thevehicle combination.

A drawback in the above-mentioned arrangements is in that each of theactuators accomplishes only one single operation, which has the need oftheir separate control as a result. Moreover, the construction is not assteady as one might desire.

The object of the invention is to disclose an arrangement, which makesit possible to eliminate the above-mentioned drawbacks. The invention isbased on the idea of providing two actuators between the terrain vehicleand the trailer, the actuators co-operating both in immobilizing theangle of rotation and in shifting the weight, without each of them beingdesigned for a single function only. In the practice, the ends of theactuators facing the terrain vehicle are attached to a rotary part ofthe articulation of rotation, the part being the one which in thearticulation is on the terrain vehicle side, and the other ends areattached to the above-mentioned load section pivotable relative to thebody section of the trailer. The provision above makes it possible tocontrol the actuators with their common control means and furtherimproves the steadiness of the construction.

The appended unindependent claims show some advantageous alternatives ofrealization of the arrangement in accordance with the invention, whichhelp to optimize the benefits of the invention.

In the following, the invention- is described in more detail withreference to the accompanying drawings, wherein

FIG. 1 is a side elevation view of the terrain vehicle and the trailerincorporating the arrangement in accordance with the invention,

FIG. 2 is a more detailed representation of the arrangement in sideelevational view, and

FIG. 3 is a schematic representation of the arrangement as seen from thetractive vehicle and it includes also a control diagram illustrating theoperation of the arrangement.

FIG. 1 shows a combination of a terrain vehicle and a trailer, in whichthe invention is applicable. The terrain vehicle, which is the tractivevehicle, is in this case a forest tractor A comprising a front axle 11carrying tracked wheels. A trailer B is joined to the tractive vehicle Athrough an articulation of turning 3 and an articulation of rotation 4.The trailer B comprises the middle axle 12 of the vehicle combination,and it also carries pairs of tracked wheels. The terrain vehicle andtrailer form in this case a so-called body-steered vehicle combination,in which the steering takes place by acting on the articulation ofturning 3 of the vehicle A. A rear body C is joined to the trailer Bthrough a hitch 14. The rear body has a rear axle 13 also carrying pairsof tracked wheels. The purpose of the hitch 14 is to ensure the guidingof the rear body C so that it follows the same tracks, and the actualtractive connection is provided by means of a load section which will bedescribed hereinafter. The vehicle type in question is a so-calledthree-axle, six-track vehicle combination, wherein all tracks areso-called driven rocking tracks. This kind of combination is disclosedfor example in Finnish Patent Application No. 854777, and its functionis not more analysed in this application except as to details connectedwith the invention. It will of course be understood that the inventioncan be utilized also in other types of terrain vehicle combinationscomprising a terrain vehicle and a trailer joined thereto. For example,the vehicle combination of FIG. 1 does not always incorporate the rearbody C. The term trailer shall in this context be interpreted as eithera rear section which is an integral part of a vehicle combinationsteered at the body, or as a trailer which can be detachably mountedafter a tractive vehicle.

A load section 7 is fixed to the body 9 of the trailer B through ahorizontal articulation 8. The horizontal articulation 8 provides thepivoting of the load section 7 in a vertical plane extendinglongitudinally of the trailer. The load section 7 continues towards therear in the form of a beam 7b extending longitudinally of the trailer.The beam is articulated through an articulation of rotation 15 on thebeam 7c mounted in the rear body C and retaining its alignment with thebeam 7b. The beam 7c is pivotable relative to the rear body in ahorizontal plane. Said beams carry the actual load space, whereupon theload such as felled trees can be charged for transport. A support 7d fora grab loader is mounted on the load section, and the former isconnectable to other implements as well, such as a tree harvester orprocessor for example.

FIGS. 2 and 3 show the construction of the combination in more detail atthe articulation of rotation and the trailer. The load section 7comprises a part 7a articulated on the trailer body 9 through thehorizontal articulation 8, as well as on top of said part, the actualload bearing part 7b turnable in a horizontal plane by means of aturntable 1. Said load bearing part 7b consists of the afore-mentionedrearwardly extending beam. A support 7d for the above-mentioned loaderis fixed on top of the part 7b.

The part 7a of the load section extends from the horizontal articulation8 towards the terrain vechicle A, and one end 2b of a hydraulic cylinder2, namely the piston rod of the cylinder, is pivotably attached theretoat this load section end facing the terrain vehicle. The opposite end 2aof the hydraulic cylinder 2, namely the cylinder body, is attached to apart 4a located on the terrain vehicle side in the articulation ofrotation 4. Laterally of the hydraulic cylinder 2 there is mountedanother cylinder 2' which is fixed at both its ends to correspondingpoints in a corresponding manner, and the pertinent points of attachmentare designated by reference numerals 2b' and 2a'. As it is clear fromFIG. 3, said points of attachment both in the load section 7 and thepart 4a of the articulation of rotation are located on the oppositesides of a vertical plane extending along the axis of rotation of thearticulation of rotation, said plane being denoted by a dashed brokenline D in FIG. 3. Said arrangement improves the solidity and function ofthe construction. Further, the hydraulic cylinders 2 and 2' are sofixed, that they extend in parallel relationship to each other andsymmetrically with respect to said vertical plane D when the vehicle Aand the trailer B are situated in a common horizontal plane.

In addition, two steering cylinders (not shown) are connected to thepart 4a of the articulation of rotation, these cylinders being attachedto the part 4a and to the body of the vehicle A at both sides of thearticulation of turning 3. Using these cylinders, the vehiclecombination can be steered by turning at the articulation of turning 3.

The primary principle of operation of the invention is to change the sumlength of the cylinders 2, 2' in order to cause a change in the pivotalposition of the load section 7 relative to the horizontal articulation8, and simultaneously, as said pivotal position has an effect as far ason the rear body C through the rearwardly extending beam 7b, the weightcan be shifted longitudinally of the vehicle combination to apredetermined track axle. In this predetermined position the cylinders 2and 2' are, however, free to change their lengths to a limited extentdin such a fashion, that as the length of one cylinder increases, that ofthe other decreases. This is necessary for the rotary movement of thevehicle side part 4a of the articulation of rotation 4 with respect tothe body section 9 of the trailer B. Said parts can be immobilized at apredetermined position of rotation by locking the cylinders 2 and 2' ata predetermined length, that is, the quadrangle constituted of thepoints of attachment 2b, 2b', 2a, 2a' is immobilized to a rigidconfiguration. This is to immobilize the trailer relative to thetractor, such as during loading and unloading. This forms the otherpurpose of the invention, accomplished by the co-operation of the samecylinders 2, 2' that serve to shift the weight. Broken lines illustratethe pivoting of the lead section 7 in FIG. 2 and the rotary movement ofthe lead section 7 in FIG. 3.

In the following, the operation of the invention is explained in moredetail with reference mainly to the operational diagram of FIG. 3.

The hydraulic-cylinders 2 and 2' are usual double-acting cylinders,whose work space adjacent to the points of attachments 2b, 2b' to thelead section 7 will be called the end at the lead section, and the workspace on the opposite side of the piston adjacent to the points ofattachment 2a, 2a' to the part 4a of the articulation of rotation 4 willbe called the end at the articulation of rotation. The ends at the leadsection are connected parallelly to the hydraulic fluid line 10b and theends at the articulation of rotation are connected parallelly to theline 10a. The lines 10a and 10b pass through a control block 6, by meansof which the supply of the hydraulic fluid from a pump P into thecylinders 2 and 2' is controlled. FIG. 3 represents the hydrauliccylinders at a so-called floating position, that is, the control blockis at its floating position (the block section 6b is at the lines 10aand 10b), said position permitting the hydraulic fluid to flow freelybetween the lines 10a and 10b, which means that the points 2a, 2a', 2band 2b' are free to move with respect to each other within the rangeallowed by the articulations 4 and 8. Further, both branches directed tothe respective cylinders from the line 10b are provided with on-offvalves 5, which are operated simultaneously. The on-off valves areconnected to a drive pedal. In the situation of FIG. 3 the on-off valvesare open allowing the flow of the hydraulic fluid in the branches of theline 10b which are connected to the cylinders 2 and 2'.

As the vehicle combination is moving, the drive pedal is held down,which maintains the open position of the on-off valves 5. At the sametime the control block 6 is in its floating position shown in thefigure. The horizontal articulation 8 is thereby free to pivotalmovement, but the elongate beam 7b, 7c extending to the rear body C andpossibly bearing a load thereupon, ensures that the support of theloader does not cause the tilting of the body section 7. When theoperator wants to use the cylinders 2 and 2' for shifting weight inorder to change the axle weights, the control block 6 is shifted to themiddle position, whereat it closes the communication between the lines10a and 10b (block section 6c situated at the lines 10a and 10b). Atthis stage the hydraulic fluid moves freely in a closed circulationbetween the same ends of the cylinders, that is, between the ends at theload section in the branches of the line 10b, and between the ends atthe articulation of rotation in the branches of the line 10a. The pointsof attachment and the cylinders are so dimensioned that as thearticulation of rotation 4 is rotated, in a vertical plane that isperpendicular to the longitudinal axis of the vehicle the changes of thevolume of the hydraulic fluid in the same ends of the cylinders 2 and 2'are always of substantially equal absolute value and have oppositedirections so that the hydraulic fluid exiting from one cylinder will bewell accommodated within the work space on the same side in the othercylinder. Hence, the load section 7 will always remain at apredetermined level determining the distribution of the axle weights,regardless of the movement of the articulation of rotation 4. Thesymmetrical location of the cylinders 2 and 2' with respect to the planeD results in the practice to cylinder strokes of equal length, in otherwords, a flow of a predetermined magnitude from/to a cylinder effects anequal change of length in both cylinders.

As the operator wants to change the position of the load section 7 andconsequently the axle weight distribution, the sum length of thecylinders will be changed. For example, by shifting the control block tothe rightmost position (block section 6a at the lines 10a and 10b) thehydraulic fluid flows from the pump P to the line 10b causing a decreasein the sum length of the cylinders, the load section 7 is tilted closerto the vehicle A and the weight will be shifted more on the middle axle12. Correspondingly, as the control block is in the leftmost position(block section 6d at the lines 10a and 10b), the hydraulic fluid willflow to the line 10a, the load section 7 will be tilted more away fromthe vehicle A and it will transmit the weight through the beam 7b moreon the rear axle 13. In this event more weight will be shifted on thefront axle 11 as well. After these steps the control block 6 can befurther shifted to its middle position, where the lines 10a and 10b areseparated from each other.

As the machine is stopped/the drive pedal is unoperated and the on-offvalves 5 will automatically shift in line with the branches of the line10b causing the locking of the cylinders 2 and 2' at the particularlength which they had at the moment of freeing the drive pedal. In thisevent the articulation of rotation 4 is immobilized, as is also the loadsection 7. By virtue of this the machine is stable on loading andunloading, because the tilting point is at the outer edge of the machineand the whole weight of the machine can be utilized. As the machine isstarted, the drive pedal is actuated again, causing the opening of theon-off valves 5 and the fluid is again free to flow between the ends ofthe cylinders 2 and 2' at the lead section 7.

As the vehicle combination is used for example as a tree harvester, therear body C has been detached from the combination, which in this casewill be two-axled. The function is in this case similar, for examplewhen driving, the on-off valves 5 are open. The control block mustthereby be at the middle position (6c), which enables the maintaining ofthe loader support in the lead section 7 in its place (the horizontalarticulation 8 is not pivoted) regardless of the position of thearticulation of rotation 4. When the machine is stopped, the on-offvalves 5 are closed and the articulation of rotation 4 is immobilized.If the operator wants to adjust the position of the loader support itcan be accomplished by moving the lead section 7 by changing the lengthof the cylinders 2 and 2' by means of the control block 6. When doingso, the on-off valves 5 are to be opened when the machine is standing.

The invention is not restricted only to the embodiment disclosed in thepreceding description and the accompanying drawings, but it can bemodified within the scope of invention presented by the claims. Theactuators can be also other kinds of actuators having a variable length,such as for example a threaded shaft, which can be shifted by means of athreaded sleeve. The operations controlling said means can be providedalso electrically, for example in an analogous manner in compliance withthe afore-disclosed hydraulic diagram. When the arrangement is used inconnection with vehicle combinations having a hydraulic drive, it is ofcourse advisable to use hydraulically operated cylinders as actuators.It will also be understood, that the controlling operations of thedevice may be provided in an alternative fashion and they may beincorporated in various ways in the control logic of the vehiclecombination.

We claim:
 1. A load distributing and articulating system in an allterrain vehicle of a tractor and a trailer along a longitudinal axis,the trailer having a trailer body with a load section thereon, whichcomprises:(i) a first pivot for articulating rotation between thetractor and the trailer in a vertical plane perpendicular to thelongitudinal axis, about the longitudinal axis; (ii) a second pivot forarticulating rotation between the trailer body and the load section, ina vertical plane along the longitudinal axis about an axis perpendicularto the longitudinal axis; (iii) at least two variable length actuatordisposed between the tractor and the load section for controlling therotation about said first and second pivots; (iv) an adjustablecontroller having a plurality of positions, for varying the lengths ofsaid variable length actuators together, and for allowing a variation ofthe lengths of said variable length actuators independently of eachother; and (v) means for preventing said adjustable controller fromvarying the lengths of said variable length actuators, and for enablingvariation of the lengths of said variable length actuators.
 2. A loaddistributing and articulating system in an all terrain vehicle having atractor and a trailer load section arranged along a longitudinal axis,the trailer load section being arranged over a trailer body, whichcomprises a first pivot between the tractor and the trailer body, saidfirst pivot having a part at said tractor and another part at saidtrailer body, a second pivot between the trailer body and the trailerload section, a pair of two ended variable length actuators eachattached at one end thereof to the trailer load section for shiftingweight to various points along the longitudinal axis, the other ends ofeach of said variable length actuators are attached to said part of saidfirst pivot at the tractor, a variable position controller attached fromsaid first and said second variable length actuators for changing thetotal length of said variable length actuators to cause a change in theangle between the trailer load section and the trailer body and therebyshift said weight, and for locking the length of said variable lengthactuators in a preselected position for maintaining a constant pivotangle between the tractor and the trailer, one end of each of said firstand said second variable length actuators is attached from said firstpivot part on the tractor, and the other end of each of said first andsaid second variable length actuators is attached along opposite sidesof a vertical plane extending along the axis of rotation of said firstpivot, in a given position of said variable position controller, achange in the angle of rotation of said first pivot causes a change inthe length of said first variable length actuator that is in theopposite direction than the change in the length of said second variablelength actuator.
 3. The load distributing and articulating system ofclaim 2, wherein both of said first and said second variable lengthactuators are identical to each other.
 4. The load distributing andarticulating system of claim 2, wherein both of said hydraulic cylindersare identical to each other, and are connected parallel to each other byhydraulic lines.
 5. The load distributing and articulating system ofclaim 2, wherein similarly located ends of said two actuators areconnected with each other through hydraulic lines said variable positioncontroller being adapted to block the flow of hydraulic medium betweenoppositely located ends of said actuators but to permit the flow ofhydraulic medium through hydraulic lines between said similarly locatedends.
 6. The load distributing and articulating system of claim 5,further comprising selective blocking means for selectively blocking andpermitting the flow of hydraulic medium in a hydraulic line between saidsimilarly located ends.